Electrodeposition of tin



was Apr. 24,. 1923.

g UNITED STATES PATENT OFFICE.

LOUIS D. SIMPKINS, 0F BROOKLYN, YORK, ASSIGNOB '10 NATIONALLEAD COMPANY, OF NEW' YORK, N. Y., A CORPORATION OF NEW JERSEY.

'mcrnonnrosrmon or TIN.

No Drawing.

To allwkomitmar concem:

Be it known that I, LouIs D. Srmrmns, a citizen of the United States, residing in Brooklyn, New York, U. S. A., have invent- 6 ed the following. described Improvements i. in the Electrodeposition of Tin.

The object of this invention is to improve the process of electrolytic deposition of tin as 'for example in. tin refining or tin-plating and consists'in the composition of the bath and more particularly in the combination of a"certain addition agent 'for use with the tin-salt solution to constitute the bath. According to this invention the salt solution is preferably stannous sulphate although other salts may be used, and the addition a ent consists of beta-naphthol and a suitable colloid which are added to the salt solution in small amounts successively or as a mixture. And in general, as is well known in the art, the addition agent is added in amounts ranging from .01% to 2% by weight of the electrolyte, which proportions may be regarded as the minimum may be conveniently prepared by elec- 30 trolytically dissolving tin in sulphuric acid by the aid of a porous cell as well understood in this art and so a's'to leave some excess of free acid, in the solution, say about 10%. The beta-naphthol is added in the proportion of about one gram per litre of-the electrolyte, and in orderto render it miscible therewith it is dissolved in a small quantity of ethyl alcohol and in troduced as a solution. The colloid is added in aboutthe proportion of two grams to the litre being first dissolved in water to make about a 10% solution. The addition a'gent thus comprises beta-naphthol and a colloid in the proportions of one to two and as above stated they may be added, mixed together, or successively. While hidejgl'ue and other like substances may be usefully .employed as the colloidal component, it is found that one of the peptones such for extone, which is quite soluble in water, forms the mostelective combination with the betanaphthol and the use of this particular .and maximum in this particular instance,

ample as the common pharmaceutical pep-.

Application filed February 10, 1922 Serial No. 535,591.

colloid in such combination is the preferred form of this invention.

The effect of this composite addition agent in the bath, is manifested by the deposit on the cathode of a compact, homometallic tin which when used for tin-plating forms an adherent 'coating naturally so bright as to require very little subsequent destroy the elfect of the beta-naphthol and the colloid, are included in this invention. I am aware that peptone has been heretofore suggested or employed as an addition agent in electrolytic tin-salt solutions and also that beta-naphthol has been suggested as an addition agent for certain other salt solutions but I believe myself to have been the first to discover-the particular utility of the combination of beta-naphthol and peptone or equivalent colloid, in a tin-salt solution as a means of obtaining the results above referred to and this patentis intended to cover that discovery without limitation except as specified in the followmg.

Claims: 1. An electrolytic bath for depositing tin, containing a tin-salt solution and small amounts of beta-naphthol and a colloid.

2. An electrolytic bath for depositing tin, containing a tin-salt solution with free acid and small a colloid.

3. An electrolytic bath for depositing tin containing stannous sulphate and small quantities of beta-naphthol and a colloid.

4. An electrolytic bath for depositing tin,

comprising stannous s p with free Sulioo quantities of beta-naphthol and 'geneously dense and coherent layer of.

6. An electrolytic bath for depositing tin,

comprising a tin-salt solution and small amounts ofbe'ta-naphthol and peptone.

' 7. An electrolytic bath for the deposition 5 of tin, containing stannous sulphate, and

small amounts of beta-n'a tone.

phthol and a pep- 8. An electrolytic bath for depositing tin, comprising stannous sulphate, free sulphuric and and small "amounts, of betanaphthol and a peptone.

In testimony whereof, I have signed this specification.

,r LOUIS D. SIMPKINS. 

